Study Of Photodegradation On Typical Phenolic Pollutants By Nitrocellulose Membrane In Aqueous Solution

Phenolic compounds,which are aromatic hydroxyl compounds,have biological toxicity and are difficult to be biodegraded.The phenolic compounds pollution by man-made emissions may cause serious pollution of water environmental and endarger people's health.Advanced oxidation processes have been widely used in the treatment of refractory organic contaminant,because of their advantages,such as strong oxidation,no secondary pollution and manageable.Three typical phenolic pollutants?p-nitrophenol,acetaminophenol and bisphenol A?as the research objects and Nitrocellulose Membrane?NCM?as a new photochemical material were selected in this study.The photodegradation effect of phenolic pollutants by nitrocellulose membrane was studied,characterization and evaluation of reaction system were analyzed,and the degradation mechanism of the reaction system was preliminarily discussed.We drawn the following conclusions:?1?Under the irradiation of the simulated light source?wavelength>280 nm?,the direct photodegradation rate of three phenolic pollutants in pure water were 9.52×10^-4min^-1,8.89×10^-5 min^-1 and 6.39×10^-5 min^-1,respectively.Nitrocellulose membrane could significantly promote the photolysis of the three phenolic pollutants,with corresponding photodegradation rate of 5.45×10^-3 min^-1,4.99×10^-3 min^-1 and 2.85×10^-3min^-1,respectively.?2?The effects of different dissolved substances on the photolysis of three typical phenolic pollutants by nitrocellulose membrane were different dramatically.For anions,NO₃^-promoted the photolysis of three phenolic pollutants.Cl^-promoted the photolysis of acetaminophenol.CO₃^2-inhibited the photolysis of p-nitrophenol and bisphenol A.SO₄^2-promoted the photolysis of acetaminophenol and inhibited the photolysis of bisphenol A.For cations,Ca²⁺and Mg²⁺promoted the photolysis of acetaminophenol.DOM inhibited the photolysis of p-nitrophenol and bisphenol A by nitrocellulose membrane through the photoshielding,and promoted the photolysis of acetaminophenol.H₂O₂ could synergize with nitrocellulose membrane to promote the photolysis of phenolic pollutants.?3?Water environment factors had an important influence on the photolysis of three typical phenolic pollutants by nitrocellulose membrane.Acidic conditions were favorable for the photolysis of p-nitrophenol.At solution pH 2.0,the corresponding photodegradation rate was 0.0165 min^-1.Alkaline or neutral conditions were favorable for the photolysis of acetaminophenol.At solution pH 8.0,the corresponding photolysis rate was 0.0096 min^-1.For bisphenol A,at solution pH 9.0,the corresponding photolysis rate was 0.0310 min^-1.The effect of nitrocellulose membrane on the photolysis of phenolic pollutants were positively correlated with light intensity,temperature and membrane area,and was more appropriate for the photolysis of organic pollutants with low concentration.?4?The quantitative analysis of the photoinduced·OH process on nitrocellulose membrane showed that the quantum yield of the photoinduced·OH was 1.31×10^-4,which was 1.88 times higher than that of the traditional photocatalytic material TiO₂.The cumulative production of·OH at next 60 min reaction was higher than that at first60 min reaction.The mechanism of the formation of·OH was that the-NO2 group on the cellulose nitrate was stimulated by simulated light to generate·OH with strong oxidation.The analysis showed that,with regard to the nitrocellulose membrane photochemical system,the target pollutants were difficult to be completely mineralized,and the products were mostly small molecular organic compounds.